Instrument and Instrument Configuration Restrictions

At each Gemini telescope, instruments are mounted at the Cassegrain focus on the
instrument support structure (ISS). A science fold mirror mounted inside the ISS can be rotated to send the light from the telescope to any of four side-looking ports, or can be retracted so that the light goes to the up-looking port. At each site, the calibration unit and the Adaptive Optics system use two of the side ports, leaving two side-looking and one uplooking port for other instrumentation. As more than three instruments are offered each semester, instrument swaps will be required and not all instruments will be available for the entire semester. Instrument swaps will be driven by demand and scheduled to minimize impact on the queue. Certain targets or entire programs may not be
feasible once the final schedule is determined, at ITAC or thereafter. Changes to the instrument mounting are not permitted during
classical runs.

If an instrument is requested for less than 6% of the Bands 1+2 time, the Observatory
reserves the right to limit the RA range available to programs, or to not schedule the instrument.
Similarly, the Observatory may choose to limit available configurations, such as
the little used R600 grating in GMOS. Investigators
applying for low-demand configurations should indicate if the science can be achieved with an alternate configuration.

Non-Sidereal Targets

Non-sidereal targets can have a broader range in RA than indicated in the Tables below due to, for example, the need to observe comets relatively close to the Sun. The ephemeris for any submitted target however must include a position that is accessible between evening and morning twilight at some point in the semester. For rapidly moving targets PIs should specify in the proposal when the target is accessible, and the coordinates of the target at that time, so that the observation can be checked for feasibility.

Gemini Frontier Fields Observations

During 2013B, some of the Gemini Director's Discretionary Time will be allocated to
use
GSAOI and GeMS
to observe two galaxy clusters that are part of the
Hubble Space Telescope Frontier Fields program. We will obtain
images of Abell 2744 and MACSJ0416.1-2403 in the
K(short) filter. We plan
to obtain approximately 5 hours on-source of each field, reaching an
estimated (point-source) sensitivity of 26.3 AB magnitudes (24.4 Vega). The available
guide stars constrain the pointings, which will be centered on
RA=00:14:18.9, DEC=-30:22:38.1 (Abell 2744) and RA=04:16:06.9,
DEC=-24:05:38.1 (MACSJ0416.1-2403) and cover the
GSAOI 85 arcsecond field of view. These data will be
immediately accessible in the
Gemini Science Archive with no proprietary
period, and we will also produce reduced images for the community after
the observations are complete. We are providing this information now to
avoid duplication of proposers' effort. Investigators who require deeper
or different but related observations should not hesitate to propose for them.

Gemini North Instrument Availability and Target Accessibility

All instruments are restricted for sky visibility as described in the Table and Figure below. In addition:

GNIRS will return to the telescope in mid-August
following a lens replacement; targets are therefore limited to RA 18h to 13.5h.

**Due to limited sky availability during the semester, GMOS MOS programs requiring pre-imaging should not have targets in this region, and other programs
with targets in this region should not require a large amount of time, or have strict timing or observing
constraints.

Gemini South Instrument Availability and Target Accessibility

All instruments are restricted for sky visibility as described in the Table and Figure below. In addition:

FLAMINGOS-2 will be available throughout the semester on a shared-risk basis, in imaging and long-slit modes only. Targets with RAs 23h to 6h are particularly encouraged, to cover the period October to November when
GMOS-South
may be unavailable.

GMOS may not be available during October and November while the CCDs are upgraded and other maintenance work is performed. The amount of time at RA 23h to 6h will therefore be limited, and investigators should indicate in the technical case of their proposal if alternate targets are available.

GSAOI + GeMS is expected to be available between September and January, limiting
RAs to 19h to 11h. Observations using GeMS are restricted to greater than
45 degrees elevation. How
this translates into RA and dec restrictions is indicated in the Table.

**Due to limited sky availability during the semester, GMOS MOS programs requiring pre-imaging should not have targets in this region, and other programs
with targets in this region should not require a large amount of time, or have strict timing or observing
constraints.

Graphical Illustration

Figure 1: Schematic representation of target accessibility at
Gemini North during semester 2013B. Green regions offer unrestricted
access, red regions are inaccessible.
Hatched areas indicate the more restricted LGS regions. The yellow region is possible, but restricted.
See text, and values in the Gemini North Table above.

Figure 2: Schematic representation of target accessibility at Gemini South during semester 2013B.
Green regions offer unrestricted access, red regions are inaccessible. Hatched areas indicate the more restricted GeMS regions (note that the limited availability of GSAOI in 13B further restricts the GSAOI + GeMS combination). The yellow region is possible, but restricted. See text, and values in the Gemini South Table above.